This invention relates to a navigation system for providing road guidance by displaying a structure-shape map showing building shapes and roads, and also to a recording medium for such a navigation system. More particularly, the present invention relates to a navigation system using a structure-shape map on which shapes of structures are displayed by coordinates strings in different display modes varying in color or other display form, together with names of the structures, to retrieve information belonging to a structure concerned and to give guidance.
A navigation system for vehicles searches, upon input of a destination or the like, for a route from a present position or a designated departing location to the destination, and provides route guidance based upon the found route. One type of guidance screen used to provide route guidance using a screen or voice based upon a suggested route found as described above is such that a map showing surroundings of the present position is displayed, and a present-location mark is displayed on the map. To enter a location or give route guidance, a map is used. Therefore, in a case where a location such as a present position or a destination is set, or the user desires to see the location of a destination on a map, a wide-area map is displayed by entering a place name such as the name of a prefecture or a city, as described above, and then maps are successively changed over from such a wide-area map to a detailed map by utilizing the map display scale, thereby displaying a desired map. Alternatively, by entering a telephone number, a map centered on the registered location is displayed.
However, to recognize information ahead of a road on which the vehicle is traveling and select a road to be taken by using a displayed map as a lead, if a large amount of information is displayed on the map, necessary information may be buried in the other information, making it difficult to precisely recognize necessary information and decide a road to be taken. In particular, in the case of a structure-shape map as described later, shapes of buildings and general houses are displayed in addition to information regarding roads. Therefore, the amount of information on the map is too large for the driver to select necessary information by looking at the map while driving. Further, it takes an exceedingly long time to draw a map containing a large amount of information. Furthermore, when the screen scroll speed is high, the drawing processing cannot be completed in time for the scrolling operation, making it impossible to make a check on a map.
In a case where a map is displayed and various guidance is given thereon, a name of a place and names of structures such as buildings, facilities and so forth are displayed as minimum and necessary information, together with the map. To display such a place name and structure names, display coordinates and display areas must be prepared in advance as data for name display separately from map data. Therefore, the conventional practice is to store name data in addition to map data.
With the conventional method in which data for map display and data for name display are prepared, however, the amount of data is unfavorably large. Moreover, a system wherein maps are displayed by changing scales needs to store data for name display for each display scale. Therefore, the amount of data increases considerably, making it necessary to use a memory of large storage capacity.
In a case where a district name and structure names are displayed on a map, it is necessary to restrict the display of names such that no names overlap each other, and the visibility of the map is not impaired. On the other hand, in an urban area congested with buildings, for example, a large number of tenants occupy one building. Therefore, to investigate such a tenant-occupied building, if there is no information regarding tenants occupying each building, it is impossible to find or verify a building where a tenant concerned resides. There has heretofore been no system capable of retrieving and showing detailed information belonging to such buildings to give guidance.
In use of a navigation system for vehicles, there are cases where the user wants to ascertain where a location such as a destination or an en-route location is as well as sets such a location. In such a case, the conventional practice is to select and enter a prefecture name, a city name, a code, a menu, coordinates, etc. to thereby display maps successively. To designate a changeover of maps from a wide-area map to a detailed map also, a plurality of key operations must be conducted. Therefore, the operation for reading out a desired detailed map is complicated and troublesome. With the method whereby, upon input of a telephone number, a map centered on the relevant location is displayed, a desired detailed map can be displayed simply by entering a telephone number, but further information cannot be acquired.
That is, although a detailed map can be displayed by entering a telephone number, if there are a plurality of items of detailed information as in the case of a complex building at the displayed location, it is impossible to ascertain whether or not the desired information is one of them. Moreover, it is impossible to acquire information regarding features and shapes of buildings, facilities and so forth which may exist at the desired location and its vicinities. For example, in a urban area congested with buildings, a large number of tenants occupy one building. Therefore, to investigate such a tenant-occupied building, if there is no information regarding tenants occupying each building, it is impossible to find or verify a building where a tenant concerned resides. There has heretofore been only map information used mainly for the purpose of providing approximate information, and there has been nothing that enables retrieval or verification of such information as information regarding complex buildings as described above and multi-purpose facilities occupied by various residents.